Synechocystis sp. PCC6803 fusB gene, located outside of the str operon, encodes a polypeptide related to protein synthesis factor EF-G.

Synechocystis sp. PCC6803, a cyanobacterium, possesses an unusual gene (fusB) which encodes a protein with strong homology to protein synthesis elongation factor G (EF-G), although it is not linked to the classical str operon. The fusB gene is redundant, since a Synechocystis gene similar to str operon-encoded fusA genes of other bacteria is also present (based on PCR and hybridization results). There is no evidence for the presence of a fusB homologue in other bacteria. The Synechocystis fusB gene encodes unusual amino acids at some positions that are highly conserved in fusA genes of other prokaryotes.